The present invention relates to a phosphor used in a fluorescent display tube, field emission display (FED), or projection tube, and In particular to a gallium nitride phosphor with superior light emitting characteristics, its method of manufacture, and a display device using the phosphor.
Gallium nitride phosphor (GaN phosphor) is a IIIb-Vb compound formed from a group IIIb elements (B, Al, Ga, In) and a group Vb elements (N, P, As, Sb). As a compound semiconductor, gallium nitride is used in single crystal thin film form for opto-electronic devices such as light emitting diodes, laser diodes, and photo-diodes, and as a high speed device material for devices such as field effect transistors. However, gallium nitride has not yet found practical application as a phosphor.
In general GaN phosphor is synthesized by firing a raw material mixture in an ambient including NH3 gas. The raw material is a mixture of Ga metal or compounds including the element Ga such as Ga2S3 and Ga2O3, with metals or compounds Including activating elements such as Zn and Mg and co-activating elements such as Si, Ge, S, and O. During firing, NH3 dissociates generating active nitrogen causing nitriding reactions to proceed, but simultaneous generation of active hydrogen causes hydrogenation of activating additives such as Zn and Mg making them Inactive. For this reason, degradation of phosphor characteristics has been a problem. In addition, moisture is produced during firing of the raw material mixture, and moisture absorbed by the phosphor during treatment remains with the phosphor. When the phosphor is used in a device, residual moisture is scattered internally and contaminates electrodes causing device performance degradation. As a result of these problems, prior art GaN system phosphors, which include large amounts of H2 and H2O, have poor luminescence characteristics, and their practical application in display devices such as fluorescent display tubes has been difficult.
Consequently, the object of the present invention is to solve the problems described above. Specifically, it is the object of the present invention to provide a gallium nitride phosphor with superior luminescence characteristics, a method of manufacture of the phosphor, and a display device using the phosphor.
The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.